1. Field of the Invention
The present invention relates to an image forming apparatus for recording an image on a sheet-like record medium such as a sheet cut to a predetermined size in an image forming section thereof, and a sheet feed apparatus for delivering the sheet-like record medium to the image forming section of the image forming apparatus.
2. Description of the Related Art
As an image forming apparatus such as a printer and a facsimile, there are used image forming apparatus of various types such as an electrophotographic type, an ink jet type, and a thermal transfer type. In most of them, in the image forming section thereof, an image such as a character or a figure is formed on a sheet-like record medium such as a sheet cut to a predetermined size.
For example, in case of the ink jet type and thermal transfer type, an image is formed on a sheet in accordance with a digital signal.
Also, in case of the electrophotographic type and electrostatic recording type, by applying a toner to an electrostatic latent image on an image carrier, a toner image is formed; and, after then, the toner image is transferred and fixed onto a sheet.
In case of the sheet onto which the image is to be applied, generally, many units of such sheets are piled up on top of another and stored in a sheet feed apparatus which is disposed within the image forming apparatus and the sheets are sequentially supplied one by one.
The sheets to be stored in the sheet feed apparatus require proper replenishment and, in order to be able to facilitate the replenishment of the sheet, there is used a sheet tray formed in a cassette which can be mounted onto and removed from the main body of the sheet feed apparatus; and, actually, the sheets are supplied to and stored in the sheet tray.
In case of such sheet tray, there is a case where only a single sheet tray is disposed in an image forming apparatus but; in many cases, in order that sheets of different sizes can be selected for application of images, two or more cassettes or sheet trays are disposed.
Also, in some of image forming apparatus, as an annex thereto, there is disposed a hand-operated tray which is convenient for arbitrary use of sheets of various sizes and various kinds.
As an ordinary image forming apparatus including a mechanism which takes out sheets one by one from a sheet tray or a hand-operated tray and feeds them sequentially to a position where an image is to be formed, there is known an image forming apparatus having a structure shown in FIG. 10.
That is, in an image forming apparatus 200 shown in FIG. 10, two sheet trays of a cassette type 204, 206 are disposed downwardly of a hand-operated tray 202.
In the deeper side of the hand-operated tray 202, there are disposed a semilunar roller 210 and a handling member 212. The semilunar roller 210, in operation, can be contacted with an upper surface of the upper-most sheet P of sheets stored in the hand-operated tray 202 and, when rotated, can send out the upper-most sheet P toward a registration roller 214.
The handling member 212 is formed of material having large friction and is used to separate the lower-side sheets P, which are delivered together with the uppermost sheet P, from the upper-most sheet P.
The sheet teed apparatus of a type using the semilunar roller 210 is advantageous in that it is relatively simple in structure and is easy to control.
However, in the above-mentioned image forming apparatus 200, there are found the following problems.
In a structure where the hand-operated tray 202 is disposed in the upper-most stage and the sheet trays 204, 206 of a removable cassette type are disposed downwardly of the hand-operated tray 202, a sheet delivery route, which extends from sheet feed rollers 216, 218 for feeding sheets P in the sheet trays 204, 206, respectively, up to the registration roller 214, is long: that is, there is a problem that height dimensions of the sheet feed apparatus and thus the image forming apparatus are large.
Also, in the case of the semilunar roller being used as the sheet feed roller, since there is a limit on the sheet delivery quantity of the semilunar roller, in an intermediate portion of the sheet delivery route between the semilunar roller and registration roller, there must be disposed a turn roller which is used to deliver the sheet up to the registration roller. This increases the number of parts and complicates the structure of the sheet feed apparatus and thus the image forming apparatus.
By the way, instead of provision of the turn roller, as in the image forming apparatus 200, in case where the sheet feed rollers 216, 218 for feeding out the sheets P of the cassette-type sheet trays 204, 206 are composed of round rollers, a mechanism (such as an electromagnetic clutch) for controlling the delivery quantity of the sheets P must be connected to the sheet feed rollers 216, 218. This increases the number of parts as well as complicates the structure and control of the sheet feed apparatus and thus the image forming apparatus further.
The present invention aims at eliminating the above drawbacks found in the sheet feed apparatus according to the related art as well as in the image forming apparatus according to the related art. Accordingly, it is an object of the invention to provide an image forming apparatus which can control the height dimensions of a sheet feed apparatus down to a low level, can minimize the number of parts and thus can simplify the structure thereof.
According to a first aspect of the invention, there is provided A sheet feed apparatus comprising:
a first sheet tray;
a second sheet trays disposed in a lower direction with respect to the first sheet tray;
a first sheet feed roller contacting with top one of sheets piled up to be stored in the first sheet tray, the first sheet feed roller adapted to feed the sheets;
a first handling member adapted to cooperate with the first sheet feed roller to prevent a plurality of the sheets stored in the first sheet tray from being fed together;
a second sheet feed roller contacting with top one of sheets piled up to be stored in the second sheet tray, the second sheet feed roller adapted to feed the sheets stored in the second sheet tray;
a second handling member adapted to cooperate with the second sheet feed roller to prevent a plurality of the sheets stored in the second sheet tray from being fed together; and
a registration roller adapted to nip the sheets fed out from the first sheet tray and the sheets fed out from the second sheet tray to deliver the both sheets to an image forming section disposed in an upper direction with respect to the first sheet feed roller,
wherein the registration roller is disposed between a first tangent line passing through a handling portion between the first sheet feed roller and the first handling member, and a second tangent line passing through a handling portion between the second sheet feed roller and the second handling member.
Next, description will be given of an operation of the sheet feed apparatus according to the first aspect of the invention.
Firstly, the first sheet feed roller is contacted with the upper-most sheet of the sheets piled up and stored in the first sheet tray to feed the upper-most sheet to the registration roller side. In this operation, the first handling member cooperates with the first sheet feed roller to prevent two or more units of the sheets from being fed together. The first handling member is used to prevent the sheets arranged downwardly of the upper-most sheet from being fed together with the upper-most sheet. Therefore, the first handling member, naturally, is disposed downwardly of the first sheet feed roller and the sheet delivery direction downstream side of the first handling member is inclined obliquely upwardly.
Next, the second sheet feed roller is contacted with the sheets piled up and stored in the second sheet tray to thereby feed the sheets to the registration roller side. In this operation, the second handling member cooperates with the second sheet feed roller to prevent two or more units of the sheets from being fed together. Since the second handling member is also a member to prevent the sheets arranged downwardly of the upper-most sheet from being fed together with the upper-most sheet, the second handling member, naturally, is disposed downwardly of the second sheet feed roller and the sheet delivery direction downstream side of the second handling member is inclined obliquely upwardly.
In case where the sheet is fed to the registration roller, the sheet is then delivered to the image forming section by the registration roller.
Here, since the registration roller is interposed between the first tangent line passing through the handling portion between the first sheet feed roller and first handling member, and the second tangent line passing through the handling portion between the second sheet feed roller and second handling member, in case where the first sheet feed roller, the second sheet feed roller and the registration roller are disposed such that they are close to one another, the position of the registration roller can be lowered, thereby being able to minimize the height dimensions of the sheet feed apparatus.
According to this, in response to requirement, as the first sheet feed roller and the second sheet feed roller, there can be used a semilunar roller which has simple in structure and is inexpensive, thereby eliminating the need for provision of turn rollers respectively between the second sheet feed roller and registration roller as well as between the first sheet feed roller and registration roller, which can in turn prevent the sheet feed apparatus from being complicated in structure.
According to a second aspect of the invention, there is provided A sheet feed apparatus comprising:
a first sheet tray;
a second sheet trays disposed in a lower direction with respect to the first sheet tray;
a first sheet feed roller contacting with top one of sheets piled up to be stored in the first sheet tray, the first sheet feed roller adapted to feed the sheets;
a first handling member adapted to cooperate with the first sheet feed roller to prevent a plurality of the sheets stored in the first sheet tray from being fed together;
a second sheet feed roller contacting with top one of sheets piled up to be stored in the second sheet tray, the second sheet feed roller adapted to feed the sheets stored in the second sheet tray;
a second handling member adapted to cooperate with the second sheet feed roller to prevent a plurality of the sheets stored in the second sheet tray from being fed together; and
a registration roller adapted to nip the sheets fed out from the first sheet tray and the sheets fed out from the second sheet tray to deliver the both sheets to an image forming section disposed in an upper direction with respect to the first sheet feed roller,
wherein the registration roller is disposed between a horizontal line passing through an upper end of the first sheet feed roller and a second tangent line passing through a handling portion between the second sheet feed roller and the second handling member.
Next, description will be given of the operation of the sheet feed apparatus according to the second aspect of the invention.
Firstly, the first sheet feed roller is contacted with the upper-most sheet of the sheets piled up and stored in the first sheet tray to feed the upper-most sheet to the registration roller side. In this operation, the first handling member cooperates together with the first sheet feed roller to prevent the sheet from being fed together with one or more of the remaining sheets. The first handling member is used to prevent the sheets arranged downwardly of the upper-most sheet from being fed together with the upper-most sheet. Therefore, the first handling member, naturally, is disposed downwardly of the first sheet feed roller and the sheet delivery direction downstream side of the first handling member is inclined obliquely upwardly.
Next, the second sheet feed roller is contacted with the sheets piled up and stored in the second sheet tray to feed the sheets to the registration roller side. In this operation, the second handling member cooperates with the second sheet feed roller to prevent two or more units of the sheets from being fed together. Since the second handling member also prevents the sheets arranged downwardly of the upper-most sheet from being fed together with the upper-most sheet, the second handling member, naturally, is disposed downwardly of the second sheet feed roller and the sheet delivery direction downstream side of the second handling member is inclined obliquely upwardly.
In case where the sheet is fed to the registration roller, the sheet is then delivered to the image forming section by the registration roller.
Here, since the registration roller is interposed between a horizontal line passing through the upper end of the first sheet feed roller and a second tangent line passing through the handling portion between the second sheet feed roller and second handling member, the height dimensions of the sheet feed apparatus can be reduced to a minimum.
According to this, in response to requirement, as the first sheet feed roller and second sheet feed roller, there can be used a semilunar roller which is simple in structure and is inexpensive, thereby eliminating the need for provision of turn rollers respectively between the second sheet feed roller and registration roller as well as between the first sheet feed roller and registration roller, which can in turn prevent the sheet feed apparatus from being complicated in structure.
According to a third aspect of the invention, there is provided a sheet feed apparatus comprising:
a first sheet tray;
a second sheet trays disposed in a lower direction with respect to the first sheet tray;
a first sheet feed roller contacting with top one of sheets piled up to be stored in the first sheet tray, the first sheet feed roller adapted to feed the sheets;
a first handling member adapted to cooperate with the first sheet feed roller to prevent a plurality of the sheets stored in the first sheet tray from being fed together;
a second sheet feed roller contacting with top one of sheets piled up to be stored in the second sheet tray, the second sheet feed roller adapted to feed the sheets stored in the second sheet tray;
a second handling member adapted to cooperate with the second sheet feed roller to prevent a plurality of the sheets stored in the second sheet tray from being fed together; and
a registration roller adapted to nip the sheets fed out from the first sheet tray and the sheets fed out from the second sheet tray to deliver the both sheets to an image forming section disposed in an upper direction with respect to the first sheet feed roller,
wherein the registration roller has two sub rollers; and a distance from a nip portion of the registration roller between the sub rollers to a handling portion between the second sheet feed roller and the second handling member is smaller than a distance from the nip portion of the registration roller to a nip portion between the first sheet feed roller and the first handling member.
In relation to a sheet feed apparatus according to a third aspect of the invention, there can also be obtained similar effects to the sheet feed apparatuses according to the first and second aspects of the invention.
According to a fourth aspect of the invention, there is provided the sheet feed apparatus according to any one of the first to third aspects of the invention, wherein in a horizontal direction, the second sheet feed roller is disposed between the first sheet feed roller and the registration roller.
According to a fifth aspect of the invention, there is provided the sheet feed apparatus according to the first to fourth aspects of the invention, further comprising a first guide portion disposed between the first sheet feed roller and the registration roller, the first guide portion adapted to guide the sheets fed from the first sheet tray toward the registration roller,
wherein the first guide portion comprises:
a first sheet curve forming portion adapted to curve a delivery direction of the sheet fed from the first sheet tray; and
a second sheet curve forming portion disposed in downstream of the delivery direction with respect to the first sheet curve forming portion, the second sheet curve forming portion adapted to curve the delivery direction of the sheet fed from the first sheet tray in an opposite direction to the curving direction by the first curve forming portion.
According to a sixth aspect of the invention, there is provided the sheet feed apparatus according to the first to fifth aspects of the invention, further comprising a second guide portion disposed between the second sheet feed roller and the registration roller, the second guide portion adapted to guide the sheets fed from the second sheet tray toward the registration roller,
wherein the second guide portion comprises at least one small-diameter roller contacting with any one of surfaces of the sheet fed from the second sheet tray to rotate.
According to a seventh aspect of the invention, there is provided an image forming apparatus, An image forming apparatus comprising:
an image forming section; and
the sheet feed apparatus according to the first to sixth aspects of the invention.
In the case of the image forming apparatus according to in the seventh aspect of the invention, the sheet fed from the sheet feed apparatus is delivered to the image forming section by the registration roller and, in the image forming section, image is recorded on the sheet.
As described in the first aspect of the invention, since the height dimensions of the sheet feed apparatus can be controlled down to a minimum, the height dimensions of the image forming apparatus can also be minimized.